20957645 has 4 divisors (see below), whose sum is σ = 25149180. Its totient is φ = 16766112.

The previous prime is 20957621. The next prime is 20957653. The reversal of 20957645 is 54675902.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15264649 + 5692996 = 3907^2 + 2386^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20957645 is a prime.

It is a super-3 number, since 3×20957645³ (a number of 23 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20957599 and 20957608.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2095760 + ... + 2095769.

It is an arithmetic number, because the mean of its divisors is an integer number (6287295).

Almost surely, 2^20957645 is an apocalyptic number.

It is an amenable number.

20957645 is a deficient number, since it is larger than the sum of its proper divisors (4191535).

20957645 is an equidigital number, since it uses as much as digits as its factorization.

20957645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4191534.

The product of its (nonzero) digits is 75600, while the sum is 38.

The square root of 20957645 is about 4577.9520530473. The cubic root of 20957645 is about 275.7068098874.

The spelling of 20957645 in words is "twenty million, nine hundred fifty-seven thousand, six hundred forty-five".